Electric vacuum head

ABSTRACT

An electric vacuum head for a vacuum cleaner has a housing, a cleaning device that can be driven by an electric motor disposed within the housing in a motor chamber, a vacuum mouth on the underside of the housing delimited by vacuum mouth edges, and a vacuum connector. The motor chamber has at least one air entry opening for entry of air to cool the electric motor, and at least one air exit opening. The air exit opening is disposed on the underside of the housing so that the cooling air that exits from the air exit opening during operation of the electric vacuum head enters into the vacuum mouth by way of at least one of the vacuum mouth edges.

CROSS REFERENCE TO RELATED APPLICATIONS

Applicants claim priority under 35 U.S.C. 119 of European Application No. 07 022 070.2 filed Nov. 14, 2007.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an electric vacuum head for a vacuum cleaner, having a housing, a cleaning device that can be driven by an electric motor disposed within the housing in a motor chamber, a vacuum mouth on the underside of the housing delimited by vacuum mouth edges, and a vacuum connector. The motor chamber has at least one air entry opening for entry of ambient air, and at least one air exit opening.

The electric vacuum head can have a rechargeable battery or also an electrical connector to the voltage supply, by way of a vacuum cleaner. Without restriction, the electric vacuum head can be connected by way of a suction tube and a flexible hose, or directly to a vacuum cleaner housing. If the vacuum head is connected directly to the vacuum cleaner housing, the weight of the vacuum cleaner rests on the electric vacuum head. The suction tube, i.e. the suction mechanism, is connected with the vacuum connector. The electric vacuum head can usually be removed from the suction tube or the vacuum cleaner housing and can be kept available as an accessory. Electric vacuum heads equipped with a rechargeable battery, in particular, can be added as accessories to all kinds of different commercially available vacuum cleaners.

2. The Prior Art

Various versions of electric vacuum heads having the characteristics described above are known. With these types of electric vacuum heads, the waste heat of the electric motor must be conducted away, in order to avoid overheating and a resulting malfunction. With a high-power electric motor, an inefficient electric motor, or stress peaks during cleaning operation, in particular, fans inherent in the motor are not sufficient to pass away the waste heat, under the installation conditions that are usually quite restricted in space. It is therefore known to utilize the partial vacuum produced by a vacuum cleaner to pass a secondary air stream over the motor chamber of the electric motor, to cool it. The electric motor has air entry openings for the entry of ambient air, and at least one air exit opening. Leaks that are present in any case, or specially provided cooling air openings can be provided as air entry and air exit openings. The air exit openings open into regions having a high partial vacuum, for example into a tilting joint assigned to the vacuum connector or into a vacuum channel within the housing. A corresponding embodiment is also known from Japanese Patent No. JP 9 047 395.

An electric vacuum head is known from Japanese Patent No. JP 5 253 125, in which the cooling air of the electric motor enters into the motor chamber through air entry openings in the housing, and gets into a roller chamber of a brush roller through air exit openings of the motor chamber. It is a disadvantage in this connection that the partial vacuum that prevails in the roller chamber, and therefore also the cooling air stream, is greatly dependent on the floor covering.

With the known embodiments, the amount of air for the vacuuming and the partial vacuum that prevails at the vacuum mouth are reduced by the secondary air stream required for cooling, and the secondary air stream that does not contribute to the vacuuming effect is also referred to as leaking air or leakage air. Because of the required minimum cooling air amount, a good seal is not possible in the known embodiments of an electric vacuum head.

SUMMARY OF THE INVENTION

Against this background, it is therefore an object of the invention to improve the vacuuming and energy efficiency of an electric vacuum head having the characteristics described initially. In particular, the amount of air for the vacuuming effect is to be maximized, while guaranteeing sufficient cooling of the electric motor.

Proceeding from an electric vacuum head having the characteristics described above, this task is accomplished, according to the invention, in that the at least one air exit opening is disposed on the underside of the housing, in such a manner that the cooling air that exits from the air exit opening during operation of the electric vacuum head enters into the vacuum mouth by way of at least one of the vacuum mouth edges. Usually, approximately ambient pressure prevails at the air entry openings of the motor chamber during vacuuming, and at least a slight partial vacuum occurs in the region of the underside of the housing into which the air exit opening opens. This causes air to be drawn in from the surroundings and passed over the motor to cool it, and to get into the vacuum mouth after it has left the air exit openings, together with the main air stream drawn in on the underside of the housing. According to the invention, the required cooling air is passed over at least one of the vacuum mouth edges, and thereby contributes to the total amount of air for the vacuuming effect. A displacement of the air intake merely takes place, viewed in the flow direction, for the partial air stream of the cooling air, in front of the vacuum mouth edges. In comparison with the known embodiments, in which the air exit opening is connected with a tilting joint, a suction channel, or a roller chamber, a comparatively slight partial vacuum prevails at the at least one air exit opening on the underside of the housing, and therefore correspondingly large flow cross-sections have to be provided. However, this is easily possible because of the large surface that is available at the underside of the housing.

Preferably, a plurality of air exit openings is provided on the underside of the housing, in order to achieve a sufficiently large flow cross-section and to avoid a malfunction in case an air exit opening is plugged up. Preferably, multiple air exit openings having essentially the same configuration are disposed next to one another. Fundamentally, air exit openings can also be disposed in front of and behind the vacuum mouth, viewed in the working direction, depending on the designs of the electric vacuum head and, in particular, on the placement of the electric motor. Then, part of the total cooling air gets into the vacuum mouth by way of the two vacuum mouth edges.

In order to guarantee a sufficient partial vacuum to transport the cooling air at the at least one air exit opening, this opening is preferably disposed in an inflow region of one of the vacuum mouth edges. In the case of a usual design of the electric vacuum head, the distance between the air exit opening and the related vacuum mouth edge is less than 30 mm, and preferably less than 15 mm.

If a sealing lip, brush strip, or the like is provided on the underside of the housing, it is practical if the at least one air exit opening is disposed between the vacuum mouth and the sealing lip or the brush strip. In addition to the pressure difference over the vacuum mouth edges, a further pressure drop is also observed at the sealing lip or the brush strip, so that a defined partial vacuum prevails between the sealing lip or the brush strip and the related vacuum mouth edge, under usual operating conditions.

By means of the configuration according to the invention, the channels, chambers, and joints along the vacuuming air stream, between the vacuum mouth and the vacuum connector, can be configured in a particularly sealed manner, without impairing the cooling, in order to minimize the occurrence of leakage air. For example, rigid and articulated connections between the parts of the electric vacuum head can be provided with seals or flexible connection hoses.

Since the cooling air contributes to the amount of air for the vacuuming effect, according to the invention, a particularly high level of vacuuming efficiency can be achieved even at a great demand for cooling air. Thus, the electric motor can easily be designed for a maximal power consumption, under load, of more than 50 W, preferably more than 100 W, and particularly preferably more than 200 W.

In one embodiment of the invention, the at least one air exit opening is disposed in a depression between ribs that preferably run approximately perpendicular to the vacuum mouth edges. By means of the ribs that run approximately in the flow direction, and the set-back arrangement of the air exit opening, blockage of the air exit opening can be prevented even in the case of a high-pile floor covering, and a sufficient air stream can be guaranteed.

Proceeding from the embodiment of an electric vacuum head that has been described above, further developments are possible. For example, cooling ribs and/or a fan wheel can be disposed on the electric motor, to support the cooling. The cross-section of the air entry opening and/or of the air exit openings can be configured to be adjustable, in order to allow adaptation to a changing demand for cooling air. In this connection, adjustment of the cross-section can take place manually or with temperature control, and the at least one air exit opening or the at least one air entry opening can be closed when the electric motor is shut off. It is also possible to variably increase or reduce the size of the flow cross-sections, as a function of different functional or power settings of the electric motor. In this connection, an electrically or mechanically driven shutter can be provided for changing the cross-section. Furthermore, automatic temperature control can also take place, by means of a temperature sensor or a shutter controlled as a bimetal shutter.

In another embodiment of the invention, a bypass is disposed on the motor chamber, which connects the motor chamber with a channel through which vacuuming air flows, or a chamber through which vacuuming air flows, within the housing. An additional air stream can be made available by the bypass, which stream allows emergency cooling in the case of an excessive reduction of the cooling air stream that flows out of the at least one air exit opening. In this connection, it is practical if the bypass is pressure-controlled and closed during normal vacuuming operation. If the vacuuming air stream decreases greatly on a very high-pile carpet or if the vacuum mouth is plugged up, for example, sufficient cooling of the electric motor may no longer be guaranteed, under some circumstances. At the same time, the partial vacuum in the channels and chambers within the housing through which vacuuming air flows increases, so that emergency cooling can be achieved by means of a bypass that opens at a predetermined partial vacuum.

In one embodiment, there is a cleaning roller disposed in a roller chamber and having lips or brush strips disposed in spiral shape, to act as a cleaning device. In this connection, the longitudinal axis of the cleaning roller is usually oriented horizontal to the working direction of the electric vacuum head. Multiple cleaning rollers disposed perpendicular or at a slant to the working direction, or other types of cleaning devices can also be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and features of the present invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention.

In the drawings, wherein similar reference characters denote similar elements throughout the several views:

FIG. 1 shows a perspective view of an electric vacuum head according to the invention;

FIG. 2 shows the electric vacuum head according to FIG. 1 in a view from below;

FIG. 3 shows a vertical section along the line III-III of FIG. 2;

FIG. 4 shows the qualitative progression of the partial vacuum Δp that prevails on the underside of the housing, along the line A-A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now in detail to the drawings, FIG. 1 shows an electric vacuum head 1 according to the invention, in a perspective view. The electric vacuum head 1 has a housing 2, in which an electric motor 4 for driving a cleaning device 5 configured as a brush roller is disposed in a motor chamber 3. The bristles of the brush roller pass through a vacuum mouth 7 that runs on the underside of housing 2, over the width of the electric vacuum head 1, and is delimited by a front vacuum mouth edge 6 a and a rear vacuum mouth edge 6 b. Sealing lips 8 a, 8 b are disposed in front of front vacuum mouth edge 6 a and behind rear vacuum mouth edge 6 b, in the movement direction. In addition to display elements 9, 9′, and operating elements 10, air entry openings 11 of motor chamber 3, for passage of air to cool electric motor 4, can be seen at the top of the housing 2. Electric vacuum head 1 has a vacuum connector 12 for a connection to a suction tube 13 or a vacuum cleaner housing, configured as a rotating/tilting joint. The voltage supply of electric vacuum head 1 can take place, without restriction, by way of a voltage source integrated into electric vacuum head 1, or by way of a feed line from the vacuum cleaner. At its rear, electric vacuum head 1 is supported by means of rollers 14.

As can be seen in FIG. 2, which shows a bottom view of electric vacuum head 1, air exit openings 15 of, motor chamber 3 are disposed on the underside of housing 2, in the inflow region of the rear vacuum mouth edge 6 b, between vacuum mouth 7 and rear sealing lip 8 b. A certain partial vacuum prevails at air exit openings 15 during vacuuming operation, so that cooling air is drawn in through air entry openings 11 and motor chamber 3, and after exit from the air exit openings 15, gets into vacuum mouth 7 by way of rear vacuum mouth edge 6 b. In this way, the cooling air contributes to the air stream for the vacuuming effect, which flows into the vacuum mouth by way of vacuum mouth edges 6 a, 6 b, thereby achieving optimization of the vacuuming effect, according to the invention.

Air exit openings 15 are disposed in a row, next to one another, at the same distance from rear vacuum mouth edge 6 b, in a depression between ribs 16 that run perpendicular to rear vacuum mouth edge 6 b. The risk of blockage of air exit openings 15 on a carpeted floor can be reduced by ribs 16 and the set-back arrangement of air exit openings 15.

In contrast to the embodiments known from the state of the art, a very tight seal of electric vacuum head 1 can be achieved even at a high power consumption of the electric motor. In this connection, electric motor 4 is typically designed for a power consumption, under load, of more than 50 W, preferably more than 100 W, and particularly preferably more than 200 W.

It can be seen from FIG. 3 that cooling air stream K passed through motor chamber 3 is passed by way of vacuum mouth edges 6 a, 6 b, and through a roller chamber 17, to vacuum connector 12, together with main vacuuming stream H that is drawn in at the side, on the underside of housing 2. Different power settings of electric motor 4 can be set using operating elements 10 shown in FIG. 1, whereby the cross-section of air entry openings 11 is adjusted using a related shutter 18, as a function of the power setting. If the total air stream that enters through vacuum mouth 7 decreases greatly, for example on a very high-pile floor covering or if vacuum mouth 7 is plugged up, sufficient cooling can no longer be guaranteed by cooling air stream K that flows by way of the air entry openings and the air exit openings. At the same time, the partial vacuum in roller chamber 17 increases as a result of the reduced total vacuuming flow. In order to prevent overheating of electric motor 4 in the case of such an operating state, a flap that opens under pressure control, in the direction of roller chamber 17, is disposed on motor chamber 3 as a bypass 19. In normal vacuuming operation, bypass 19 is closed, and opens when a predetermined partial vacuum is exceeded, thereby achieving emergency cooling by means of an emergency cooling stream N that enters directly into the roller chamber from the motor chamber.

FIG. 4 shows the partial vacuum Δp that prevails at the underside of housing 2, viewed in the longitudinal direction. In this connection, a maximal partial vacuum Δp_(max) with reference to the ambient pressure is observed in a first region I, directly below vacuum mouth 7. The partial vacuum Δp decreases greatly at vacuum mouth edges 6 a, 6 b, whereby the vacuum effect is determined, to a decisive extent, by the flow and the pressure distribution at vacuum mouth edges 6 a, 6 b. In a second and a third region II, III between a vacuum mouth edge 6 a, 6 b and related sealing lip 8 a, 8 b, a reduced partial vacuum is observed, but it is sufficient to generate a cooling air stream K to cool the electric motor 4, by way of air entry openings 11, motor chamber 3, and air exit openings 15. In a fourth and fifth region IV, V, outside of the sealing lips, approximately ambient pressure prevails.

Accordingly, while only a few embodiments of the present invention have been shown and described, it is obvious that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention. 

1. An electric vacuum head for a vacuum cleaner, comprising: a housing; a cleaning device that is driven by an electric motor disposed within the housing in a motor chamber; a vacuum mouth on an underside of the housing delimited by vacuum mouth edges; and a vacuum connector connected to the housing; wherein the motor chamber has at least one air entry opening for entry of air to cool the electric motor, and wherein at least one air exit opening is disposed on the underside of the housing so that cooling air that exits from the air exit opening during operation of the electric vacuum head enters into the vacuum mouth by way of at least one of the vacuum mouth edges.
 2. The electric vacuum head according to claim 1, wherein there are a plurality of air exit openings on the underside of the housing.
 3. The electric vacuum head according to claim 1, wherein the at least one air exit opening is disposed in a depression between ribs that run approximately perpendicular to the vacuum mouth edges.
 4. The electric vacuum head according to claim 1, wherein the cleaning device is configured as a cleaning roller disposed in a roller chamber.
 5. The electric vacuum head according to claim 1, wherein the air exit opening is disposed in an inflow region of one of the vacuum mouth edges.
 6. The electric vacuum head according to claim 1, further comprising a sealing lip or a brush strip on the underside of the housing, the air exit opening being disposed between the vacuum mouth and the sealing lip or the brush strip.
 7. The electric vacuum head according to claim 1, wherein the electric motor is designed for a maximal power consumption, under load, of more than 50 watts.
 8. The electric vacuum head according to claim 1, wherein a cross-section of at least one of the air entry opening and the air exit opening is adjustable.
 9. The electric vacuum head according to claim 1, wherein a bypass is disposed on the motor chamber, said bypass connecting the motor chamber with a channel or chamber through which vacuuming air flows, within the housing. 